The present invention relates generally to automated analytical instruments and more particularly to automated analytical instruments for use in conducting assays for components of interest in fluid samples.
In recent years, a number of automated instruments have been developed to perform analyses of fluid samples. As is known in the art, such instruments may be used to test various types of biological fluids for substances of interest, for example, to find evidence of disease, to monitor therapeutic drug levels, and the like. Typically, such automated analytical instruments utilize either liquid reagents or dry reagents to assay for a substance of interest. Various different types of assay devices are known for use in such automated instruments including, for example, dry thin-film multilayer assay elements which are typically mounted in an assay module and capillary assay devices.
Generally speaking, the testing system portion of automated analytical instruments which use assay modules to test for a component of interest typically include a fluid dispensing system for metering out a quantity of the fluid sample to be analyzed to an assay module, a temperature controlled chamber for holding the assay modules at the appropriate temperature to allow the reaction to take place, an analyzing system for measuring a detectable change brought about by the presence of the substance of interest in the fluid sample and some mechanism for conveying the assay module to each of the foregoing components in the proper order.
The assay modules may be provided by various techniques. In one type of automated analytical instrument an assay module to be used is manually loaded into an assay module transfer device. The assay module is then transferred to the test system. In U.S. Pat. No. 4,152,390, there is described an automated analytical instrument which includes, in addition to the testing system, a supply unit for holding a plurality of assay modules and a transfer apparatus for transferring an assay module from the supply unit to the testing system. The assay modules are stacked in containers, which may be received in a nest of the analyzing apparatus with a spring biased plunger arranged to enter the container through an opening. The plunger engages a movable element located in the container behind the stack of modules to urge the top module forwardly towards the testing system portion of the instrument. The transfer apparatus comprises a bell crank pivotally mounted to a frame member and having a first leg which is connected to a pusher member through a link. The pusher member is mounted for reciprocating movement in a bearing block carried on a cover member. A second leg of the bell crank is pinned to a connecting rod which transmits power to the bell crank. The rod is adapted to pivot the bell crank through a limited arc which in turn causes the pusher member to reciprocate in and out of the cartridge. As the pusher member moves into the cartridge, it engages a slide and moves it from the cartridge into a metering position directly under the metering tip.
In copending, commonly assigned United States patent application Ser. No. 732,053 filed on Jul. 18, 1991 in the name of Robert C. Maclndoe, Jr., there is disclosed an example of an automated analytical instrument of the type which uses assay modules to perform assays for components of interest in fluid samples. The instrument includes a fluid sample cup holder having a plurality of fluid sample holding cups, a supply apparatus for holding a supply of assay modules, a testing system which includes apparatus for testing the fluid sample using the assay modules, and an assay module transfer apparatus for transferring an assay module to be used from the supply apparatus to the testing system. The assay module transfer apparatus includes an assay module transfer unit which is mounted on a supporting structure and is movable vertically. The assay module transfer unit includes a mechanism for pulling an assay module out from the supply apparatus and a mechanism for pushing the assay module so obtained into the testing system. By moving the assay module transfer unit vertically, the assay module transfer unit can be aligned with assay modules disposed at different vertical locations within the supply apparatus.
As can readily be appreciated, automated analytical instruments which include an automated mechanism for transporting assay modules stored within the instrument to the testing system are desirable since they do not require an operator to manually feed assay modules, one at a time, into the testing system. As the state of the art with respect to automated analytical instruments advances there is a continuing desire for improved mechanisms for use therein including new and improved assay module transport mechanisms for transporting assay modules from an assay module supply apparatus to the test system.